Remediation of landfill for infrastructure works

Overview

Remediation of zones through a former landfill so as to establish a safe workplace for contractors to construct pipe network and other services for the desalination plant. Two major service trenches were excavated to specific design levels and contaminated spoil was transported and disposed offsite to landfill.

All contaminated material was managed in accordance with EPA requirements and asbestos supervision and controls were implemented as required throughout the project. Continuous dewatering was undertaken throughout the excavation works to allow excavation to design levels and contaminated water was treated and disposed to sewer under trade waste. A number of live services, including water, sewer, electrical, telecommunications and stormwater were encountered during excavation works which required removal and/or diversion and re-instillation to allow excavation works to proceed. This included the removal and replacement of a live section of sewer rising main. Upon completion of excavation works a geofabric marker was installed to the trench profile and trenches were backfilled under AS1 geotechnical supervision.

Summary

• Excavation of service trenches through a former landfill to specific design requirements
• Transport and offsite disposal of approximately 10,000m3 of contaminated soil generated from the excavation of the service trenches
• Contaminated materials management throughout the duration of the excavation works including materials tracking and asbestos management
• Location, removal and/or diversion and re-instillation of a number of services (water, sewer and stormwater) to allow continuous excavation of the service trenches. This included the removal and replacement of a live section of sewer rising main.
• Continuous dewatering throughout the excavation works, treatment and disposal of contaminated water to sewer under a trade waste agreement
• Installation of geofabric marker layer to trench profile
• Controlled backfilling of service trenches with engineered fill under AS1 geotechnical supervision

Excavation and remediation for construction of Charlestown extensions

Overview

Project involved all bulk and detail excavation and remediation works to enable the construction of the new extension of the Charlestown Square Shopping Centre, The New Charlestown Bowling Club, Kahibah Child Care Centre, St Johns Sport Field and all road works required for the construction.

Summary

• Disconnection of existing services and removal of redundant underground stormwater and sewer service
• Strip to stockpile 6,500 m3 of topsoil.
• Excavate, segregate, cart, spread for re-use in a different site and compact 20,000 M3 of inert/VENM soil.
• Excavate and dispose of 4,000m3 of Asbestos impacted Soil.
• Cut to fill 30,000m3 of Asbestos Impacted soil followed by capping with marker layer and 6,000m3 of engineered clay cap.
• Chase and excavate to stockpile 850m3 of slag impacted soil.
• Construction of on-site slag encapsulation cell including the supply and installation of GCL layer.
• Bulk excavation, batters and sub grade trimming to accommodate all roads, basements, car parks and ground slabs.
• Detail excavation required for the installation of new services, pile caps and foundations required for the construction.

Remediation of the former Armidale Gasworks Site

Overview

This project involved the remediation of the former Armidale gasworks site required to enable construction of the future West End Market Place in Armidale, NSW. The site area is approximately 1.7 ha.

Summary

• Installation and maintenance of erosion and sediment control measures
• Disconnection of existing services and demolition and removal of former gasworks infrastructure
• Demolition and removal of redundant underground stormwater, gas and sewer services
• Excavate, segregate and stockpile of approx. 25,000 tonnes of Inert, Solid, Industrial and Hazardous waste
• Conduct Hazardous waste treatment trial
• Remediation of contaminated soils therein including treatment of 15,000 tonnes of coal tar impacted soils
• Design, supply, install and operate water treatment unit to treat 400 km3 of contaminated underground water prior dispose to sewer
• Construction of 8 m vertical barrier wall around perimeter of 1.7 ha former Armidale gasworks site, barrier layer, GCL, drainage layer, gas vents and monitoring wells
• Supply and placement of engineered base materials across site
• Excavation, treated timber piles, steel and concrete to pile caps, stripfootings, loading deck and all foundations for the West End Market Place